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Mix n match re gigabit and 10/100

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Mediaman

Regular Contributor
1) Suppose one has a fully configured gigabit network (cards, switches,routers,etc) What, if any, impact would there be on LAN performance, if :

a) a wired computer with a 10/100 network card is added . Does it slow down the entire LAN, or is only that connection affected?

b) a non-gigabit wireless router, set up as a wireless access point, is added... ie ethernet cable connected to it 10/100 LAN port. I assume there would be no WAN impact( ie one is typically limited to 5-10Mbps max speed anyway), but is the LAN affected as there is now a device connected to a 10/100 port?​

2) Reverse question.. if one primarily has a 10/100 LAN, and if some machines happen to have a gigabit card, do they offer any advantage?
 
In a switched network, connections are made client-to-client. The only time gigabit clients are affected is when communicating with slower clients. In that case, the gigabit client slows to the 10/100 client's speed.

If gigabit clients are connected to a 10/100/1000 switch, they will operate among themselves at the faster rate. As noted above, gigabit clients offer no advantage when communicating with 10/100 Mbps clients.
 
Mix n Match, but with VLAN?

If you introduce a VLAN into above mix of 100/1000 devices, and segment the 1000's togethers and the 100's together and then share the two segments, does the same problem occur (meaning the flow control issue)?

Craig
 
A followup to 1b above.

Say a non-gigabit wireless router, set up as a wireless access point, is connected to via ethernet cable connected to its 10/100 LAN port.

Does this mean that it can never achieive the >100 throughput we see on the wireless charts? That is, all those routerss with >100 throughputs must have gigabit ports??
 
The following article provided results of investigation of reported claims of 100 Mb/s devices slowing down gigabit connections:

http://www.smallnetbuilder.com/content/view/30212/54/

Good find! Disabling flow control - who knew. I went to disable it on my Intel 82566DC and noted it was disabled by default.

Questions

1) does this feature only apply to gigabit cards or must one find and disable flow control on 10/100 cards?

2) with flow control disabled, as per the article, while this might affect max thoughput, its the lessor of two evils and is better than enabling flow control.....correct?
 

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Flow control really only affects the scenario described in the article.

I doubt you'll see an effect on maximum throughput.
 
This sound interesting to disable the flow control, but only gig nics and not on 10/100 nics.

I have a network here that uses both 1000mbps and 100mbps plus wireless.

Wireless - DIR-655 router


100mbps
(port1- connects to external unmanaged 100mbps 128KB packet buffer 5-port switch) - uplinks to second external unmanaged 100mbps 64KB packet buffer 8-port switch) - uplinks to third external unmanaged 100mbps 64KB packet buffer 5-port switch) connects to 2 media network players and wireless access point which supports second and third floor wireless devices.

1000mbps
(port4 - connects to external unmanaged 1000mbps 128KB packet buffer 5-port switch) - uplinks to second external umanaged 1000mbps 128KB Packet buffer 5-port switch) manage two servers and two desktop PCs with gig nics.

I have not disable flow control as of yet. I did try jumbo frames set to 4K I didn't seem anything changed in how I move media files in size of 300MB to media server. Under 100mbps it use to take 40 to 45 seconds, now it like 10 an less and with 3GB use to take under 100mbps about 4 mins now it 2 mins under gig.

I did see your review on the 8-port gig round up. Netgear GS608 with 128KB buffer looks great, but I don't need 8-ports even though I did but a pair of the new green GS605 5-ports for 10 ports. I ways prepare for the future needs. I did see that GS108 didn't do so well which cost more being metal over plastic. I already had the 2x FS105 64KB and 1x FS108 96KB prior. Plus Linksys 2x 5-port (still odd suppose to have 1MB it has to be less) switches and 1x 8-port 256KB.
 
All devices on a network beiteither 10/100/1000gigbit or a 10/100 megabit client all the other client devices on the lan will auotonegotioate to a common sped to a void incompatibility bottle nicks and provide absolute 100% up time. IMHO unless you ar planning to pjase out all of the 10/100 mgabit nics on you network don't bother goin up to 10/100/1000 infrastructure.

Anoter snafo is that very few Internet Service Providers acturally provide 'tue gigbit' service menain both gigabit up and downstream bandwidth, the next best thing is 6msg up 25megabit down/upstream bandwidth (cable provideras (i.e. Comcast, Cox Communications and others).
 
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